The present invention relates generally to fuel tank caps and relates more particularly to a fuel tank cap having a fuel inlet passage therein with automatic valve means for closing said fuel passage upon removal of the cap from a tank.
Fuel tank caps have long been employed to close the aperture through which fuel is introduced into the tank, which normally comprises a raised tank neck portion into which a fuel nozzle may be inserted. A variety of fuel tank caps have been proposed, some having threaded fastener elements for securing the cap to the tank, and others having locking ears cooperating with the tank neck flange in conjunction with a cap spring to hold the cap in place. Typically, fuel tank caps have some form of vent means to permit entrance of air into the tank as fuel is consumed, but preventing gas vapors from escaping into the atmosphere.
The present invention is directed particularly to fuel tank caps for portable marine fuel tanks of the type used with outboard motors. Such tanks typically have a capacity of about six gallons and are thus light enough to be portable even when filled. Their small capacity, however, limits the range of the boat if only a single tank is employed, and it has thus become common to utilize a plurality of such tanks either independently, or more desirably, ganged in series to extend the boat's range.
If the plurality of tanks are used independently, the engine may run out of fuel at an inopportune moment, preventing manueverability of the boat until a new tank is connected. Such an interruption of power is potentially dangerous and, in any event, delays the progress of the boat's passage.
It is accordingly preferable to connect the plurality of tanks in series so that when a given tank becomes empty, fuel will be drawn from the next tank in the series. In U.S. Pat. No. 3,158,193, a fuel supply system is illustrated wherein fuel is drained first from the tank closest to the engine and then from the next closest tank, etc. In another system shown in U.S. Pat. No. 3,409,040, the fuel is drained first from the farthest tank from the engine followed by the next closest, etc.
Regardless of which type of system is used, a common feature of the ganged fuel tanks is a flexible fuel conduit joining one tank to another. To avoid requiring modification of the fuel tank, it is preferable to lead the fuel conduit from the fuel pick up tube of one tank through the fuel cap of the adjacent tank, which arrangement is shown in U.S. Pat. No. 3,409,040. A disadvantage of such a system is the spillage of fuel which is likely to occur when the filler cap is removed. Any fuel remaining in the fuel line will flow from the removed cap should be set down at a lower elevation than the remainder of the line. On boats, any fuel spillage is a matter of serious concern, since gasoline fumes being heavier than air will accumulate in the lowest region of the boat with the potential for explosion.
The present invention prevents such fuel spillage by providing automatic valve means which closes the fuel inlet passage in the valve cap upon removal of the cap from the fuel tank.